Community In Guinea-Bissau Research Articles

Smoke, Dust, and Blood

Smoke, Dust, and Blood

Decoupling Capacitance Enabled Water Pumping System using Photovoltaic System

A two-stage PV water-pumping system architecture is represented in this paper. In contrast with other alternatives available in the literature, the electronic drive does not exploit batteries to accomplish energy decoupling, neither large electrolytic capacitors in between stages. Although these two design decisions respectively minimize environmental impacts and increase the converter’s expected lifetime, they also bring about considerable control difficulties. More specifically, the DC link stiffness is reduced and thus large voltage oscillations may occur. In order to overcome this problem, a nonlinear controller interconnection between the individual compensator of each stage is created to account for the low capacitance. Simulations and experimental results demonstrate the effectiveness of the method in stabilizing the DC-link voltage under sudden solar irradiation changes. The final converter was deployed in a remote rural community in Guinea-Bissau for crop irrigation purposes. Despite the harsh conditions such as high temperatures and sea breeze, in situ results were satisfactory and validated the system robustness

Decoupling Capacitance Enabled Water Pumping System using Photovoltaic System

A two-stage PV water-pumping system architecture is represented in this paper. In contrast with other alternatives available in the literature, the electronic drive does not exploit batteries to accomplish energy decoupling, neither large electrolytic capacitors in between stages. Although these two design decisions respectively minimize environmental impacts and increase the converter’s expected lifetime, they also bring about considerable control difficulties. More specifically, the DC link stiffness is reduced and thus large voltage oscillations may occur. In order to overcome this problem, a nonlinear controller interconnection between the individual compensator of each stage is created to account for the low capacitance. Simulations and experimental results demonstrate the effectiveness of the method in stabilizing the DC-link voltage under sudden solar irradiation changes. The final converter was deployed in a remote rural community in Guinea-Bissau for crop irrigation purposes. Despite the harsh conditions such as high temperatures and sea breeze, in situ results were satisfactory and validated the system robustness

A Battery-Less Photovoltaic Water-Pumping System With Low Decoupling Capacitance

A two-stage photovoltaic water-pumping system architecture is presented in this paper. In contrast with other alternatives available in the literature, the electronic drive does not exploit batteries to accomplish energy decoupling, neither large electrolytic capacitors in between stages. Although these two design decisions, respectively, minimize environmental impacts and increase the converter's expected lifetime, they also bring about considerable control difficulties. More specifically, the dc-link stiffness is reduced, and thus, large voltage oscillations may occur. In order to overcome this problem, a nonlinear controller interconnection between the individual compensator of each stage is created to account for the low capacitance. Simulations and experimental results demonstrate the effectiveness of the method in stabilizing the dc-link voltage under sudden solar irradiation changes. The final converter was deployed in a remote rural community in Guinea-Bissau for crop irrigation purposes. Despite the harsh conditions such as high temperatures and sea breeze, in situ results were satisfactory and validated the system robustness.

The Introduction of Diphtheria-Tetanus-Pertussis and Oral Polio Vaccine Among Young Infants in an Urban African Community: A Natural Experiment

BackgroundWe examined the introduction of diphtheria-tetanus-pertussis (DTP) and oral polio vaccine (OPV) in an urban community in Guinea-Bissau in the early 1980s. MethodsThe child population had been followed with 3-monthly nutritional weighing sessions since 1978. From June 1981 DTP and OPV were offered from 3months of age at these sessions. Due to the 3-monthly intervals between sessions, the children were allocated by birthday in a ‘natural experiment’ to receive vaccinations early or late between 3 and 5months of age. We included children who were <6months of age when vaccinations started and children born until the end of December 1983. We compared mortality between 3 and 5months of age of DTP-vaccinated and not-yet-DTP-vaccinated children in Cox proportional hazard models. ResultsAmong 3–5-month-old children, having received DTP (±OPV) was associated with a mortality hazard ratio (HR) of 5.00 (95% CI 1.53–16.3) compared with not-yet-DTP-vaccinated children. Differences in background factors did not explain the effect. The negative effect was particularly strong for children who had received DTP-only and no OPV (HR=10.0 (2.61–38.6)). All-cause infant mortality after 3months of age increased after the introduction of these vaccines (HR=2.12 (1.07–4.19)). ConclusionDTP was associated with increased mortality; OPV may modify the effect of DTP.

Giardia Duodenalis e Desnutrição Crónica em Crianças Menores de Cinco Anos de uma Região Rural da Guiné-Bissau

Malnutrition and infections by intestinal parasites such as Giardia duodenalis coexist in the same geographical regions, reaching the highest prevalence in developing countries. The cycle of malnutrition and infection implies that both conditions can aggravate each other and compromise the growth and development of children with special relevance for under-five. The aim of this study was to investigate the association between chronic malnutrition and infection by G. duodenalis in children under five in a rural community in Guinea-Bissau. A case-control study that included 109 children aged 0 to 59 months of a rural community in Guinea-Bissau was conducted. The anthropometric assessment of children in the study identified 31 cases of chronic malnutrition (z-score height for age < -2) and 78 controls (z-score height for age = -2). Microscopic examination of stools was performed for detection and identification of G. duodenalis and other parasites. The microscopic analysis of stool samples revealed G. duodenalis infection in 29.0% (9/31) of cases and 35.9% (28/78) of controls. No association between the infection with G. duodenalis and chronic malnutrition in children under study could be established. The results reinforce the interest in designing further studies exploring this association in different regions and epidemiological settings, while direct to the importance of the criteria for malnutrition definition which influences the subsequent analysis.

Maternal Proviral Load and Vertical Transmission of Human T Cell Lymphotropic Virus Type 1 in Guinea-Bissau

The relative importance of routes of transmission of human T cell lymphotropic virus type 1 (HTLV-1) in Guinea-Bissau is largely unknown; vertical transmission is thought to be important, but there are very few existing data. We aimed to examine factors associated with transmission in mothers and children in Guinea-Bissau, where HTLV-1 is endemic (prevalence of 5% in the adult population). A cross-sectional survey was performed among mothers and their children (aged <15 years) in a rural community in Guinea-Bissau. A questionnaire to identify risk factors for infection and a blood sample were obtained. HTLV-1 proviral load in peripheral blood was determined and PCR was performed to compare long terminal repeat (LTR) sequences in mother-child pairs. Fourteen out of 55 children (25%) of 31 HTLV-1-infected mothers were infected versus none of 70 children of 30 uninfected mothers. The only factor significantly associated with HTLV-1 infection in the child was the proviral load of the mother; the risk of infection increased significantly with the log(10) proviral load in the mother's peripheral blood (OR 5.5, 95% CI 2.1-14.6, per quartile), adjusted for weaning age and maternal income. HTLV-1 sequences of the LTR region obtained from mother-child pairs were identical within pairs but differed between the pairs. Vertical transmission plays an important role in HTLV-1 transmission in this community in Guinea-Bissau. The risk of transmission increases with the mother's proviral load in the peripheral blood. Identical sequences in mother-child pairs give additional support to the maternal source of the children's infection.

HTLV-1 and HIV-2 Infection Are Associated with Increased Mortality in a Rural West African Community

BackgroundSurvival of people with HIV-2 and HTLV-1 infection is better than that of HIV-1 infected people, but long-term follow-up data are rare. We compared mortality rates of HIV-1, HIV-2, and HTLV-1 infected subjects with those of retrovirus-uninfected people in a rural community in Guinea-Bissau.MethodsIn 1990, 1997 and 2007, adult residents (aged ≥15 years) were interviewed, a blood sample was drawn and retroviral status was determined. An annual census was used to ascertain the vital status of all subjects. Cox regression analysis was used to estimate mortality hazard ratios (HR), comparing retrovirus-infected versus uninfected people.ResultsA total of 5376 subjects were included; 197 with HIV-1, 424 with HIV-2 and 325 with HTLV-1 infection. The median follow-up time was 10.9 years (range 0.0–20.3). The crude mortality rates were 9.6 per 100 person-years of observation (95% confidence interval 7.1-12.9) for HIV-1, 4.1 (3.4–5.0) for HIV-2, 3.6 (2.9–4.6) for HTLV-1, and 1.6 (1.5–1.8) for retrovirus-negative subjects. The HR comparing the mortality rate of infected to that of uninfected subjects varied significantly with age. The adjusted HR for HIV-1 infection varied from 4.0 in the oldest age group (≥60 years) to 12.7 in the youngest (15–29 years). The HR for HIV-2 infection varied from 1.2 (oldest) to 9.1 (youngest), and for HTLV-1 infection from 1.2 (oldest) to 3.8 (youngest).ConclusionsHTLV-1 infection is associated with significantly increased mortality. The mortality rate of HIV-2 infection, although lower than that of HIV-1 infection, is also increased, especially among young people.

Maternal proviral load and vertical transmission of Human T cell Lymphotropic Virus type 1 in Guinea-Bissau

Abstract The relative importance of routes of transmission of human T cell lymphotropic virus type 1 (HTLV-1) in Guinea-Bissau is largely unknown; vertical transmission is thought to be important, but there are very few existing data. We aimed to examine factors associated with transmission in mothers and children in Guinea-Bissau, where HTLV-1 is endemic (prevalence of 5% in the adult population). A cross-sectional survey was performed among mothers and their children (aged <15 years) in a rural community in Guinea-Bissau. A questionnaire to identify risk factors for infection and a blood sample were obtained. HTLV-1 proviral load in peripheral blood was determined and PCR was performed to compare long terminal repeat (LTR) sequences in mother–child pairs. Fourteen out of 55 children (25%) of 31 HTLV-1-infected mothers were infected versus none of 70 children of 30 uninfected mothers. The only factor significantly associated with HTLV-1 infection in the child was the proviral load of the mother; the risk...

Increased Prevalence of HTLV-1 Among HIV-2-Infected Women but Not HIV-2–Infected Men in Rural Guinea-Bissau

To assess the prevalence of HTLV infection and its association with HIV and other potential risk factors. A cross-sectional survey and a case-control study in a rural community in Guinea-Bissau. A total of 2770 people were included in an HIV and HTLV seroepidemiologic survey. Three hundred of these participants were selected for a case-control study on HIV-2. Sera from both studies were tested for HTLV. In all, 2501 and 298 subjects in the survey and case-control study, respectively, were tested for HTLV. Overall HTLV-1 prevalence was 5.2% and it was higher in women (odds ratio [OR], 1.36; confidence interval [CI], 0.92-2.02). Apart from an infected spouse, no significant risk factors could be identified for men. In women, HIV-2 infection (adjusted OR, 5.58; CI, 3.09-10.1), having an infected spouse, and area of residence were significantly associated with HTLV-1 infection. The association between HTLV-1 and HIV-2 was significantly different for men and women (test of interaction, p =.002). In women, the most important determinant of HTLV-1 seropositivity was HIV-2 infection. Because the pattern was significantly different for men and women, common sexual risk factors may not be sufficient to explain the co-occurrence of HIV-2 and HTLV-1 in women. These observations may have implications in geographic areas where both types of retroviruses are prevalent.

Increased Prevalence of HTLV-1 Among HIV-2-Infected Women but Not HIV-2–Infected Men in Rural Guinea-Bissau

Objective: To assess the prevalence of HTLV infection and its association with HIV and other potential risk factors. Design and Setting: A cross-sectional survey and a case-control study in a rural community in Guinea-Bissau. Methods: A total of 2770 people were included in an HIV and HTLV seroepidemiologic survey. Three hundred of these participants were selected for a case-control study on HIV-2. Sera from both studies were tested for HTLV. Results: In all, 2501 and 298 subjects in the survey and case-control study, respectively, were tested for HTLV. Overall HTLV-1 prevalence was 5.2% and it was higher in women (odds ratio [OR], 1.36; confidence interval [CI], 0.92-2.02). Apart from an infected spouse, no significant risk factors could be identified for men. In women, HIV-2 infection (adjusted OR, 5.58; CI, 3.09-10.1), having an infected spouse, and area of residence were significantly associated with HTLV-1 infection. The association between HTLV-1 and HIV-2 was significantly different for men and women (test of interaction, p = .002). Conclusions: In women, the most important determinant of HTLV-1 seropositivity was HIV-2 infection. Because the pattern was significantly different for men and women, common sexual risk factors may not be sufficient to explain the co-occurrence of HIV-2 and HTLV-1 in women. These observations may have implications in geographic areas where both types of retroviruses are prevalent.

Increased prevalence of HTLV-1 among HIV-2-infected women but not HIV-2-infected men in rural Guinea-Bissau.

Objective: To assess the prevalence of HTLV infection and its association with HIV and other potential risk factors. Design and Setting: A cross-sectional survey and a case-control study in a rural community in Guinea-Bissau. Methods: A total of 2770 people were included in an HIV and HTLV seroepidemiologic survey. Three hundred of these participants were selected for a case-control study on HIV-2. Sera from both studies were tested for HTLV. Results: In all 2501 and 298 subjects in the survey and case-control study respectively were tested for HTLV. Overall HTLV-1 prevalence was 5.2% and it was higher in women (odds ratio [OR] 1.36; confidence interval [CI] 0.92–2.02). Apart from an infected spouse no significant risk factors could be identified for men. In women HIV-2 infection (adjusted OR 5.58; CI 3.09–10.1) having an infected spouse and area of residence were significantly associated with HTLV-1 infection. The association between HTLV-1 and HIV-2 was significantly different for men and women (test of interaction p=.002). Conclusions: In women the most important determinant of HTLV-1 seropositivity was HIV-2 infection. Because the pattern was significantly different for men and women common sexual risk factors may not be sufficient to explain the co-occurrence of HIV-2 and HTLV-1 in women. These observations may have implications in geographic areas where both types of retroviruses are prevalent. (authors)

HIV-2 does not protect against HIV-1 infection in a rural community in Guinea-Bissau

To examine the putative protective effect of HIV-2 infection against subsequent HIV-1 infection. Retrospective analysis of data from two cross-sectional surveys in the same community. Two surveys between 1989 and 1998 in a rural area in northwestern Guinea-Bissau provided data from residents aged 15-59 years. HIV testing was done in the first survey. In the second survey, tests were made for both HIV and syphilis, and data on sociodemographic factors and sexual behaviour, including commercial sex work, were gathered. Qualitative polymerase chain reaction amplification of HIV-1 and HIV-2 viral DNA was performed on serologically dually reactive samples. Of the 2276 eligible adult villagers initially tested, 60% (1360) provided a second sample. Of 110 HIV-2-infected subjects, 17 became additionally infected with HIV-1 [incidence rate (IR), 26.3/1000 person-years observation]. Of the 1250 HIV-seronegative subjects, 24 became infected with HIV-1 (IR, 2.8/1000 person-years observation). The incidence rate ratio (IRR), comparing the incidence rate in HIV-2-infected people with the rate in HIV-seronegative subjects, was > 1 in all three "risk groups": men, female commercial sex workers, and other women. The overall estimate of the IRR, adjusted for age group and risk group, was 3.24 (confidence interval, 1.5-7.1). There was no protective effect of HIV-2 in this population. HIV-2 cannot be regarded as a vaccine, but, instead, may be a risk factor for HIV-1 infection.

Genotype profiles of rotavirus strains from children in a suburban community in Guinea-Bissau, Western Africa.

The P (VP4) and G (VP7) genotypes of 167 group A rotavirus strains obtained during the period 1996 to 1998 from 149 children living in a suburban community in Guinea-Bissau, western Africa, were determined by the reverse transcription-PCR technique. A total of nine combinations including five different P types and five different G types were identified. The globally common genotype pairs P[8], G1; P[4], G2; P[8], G3 and P[8], G4 were underrepresented in this study area. We found a substantial year-to-year variation in the occurrence of the genotype combinations. In 1996 and 1997, P[6], G2 was the most frequent, whereas P[8], G1 was more common in 1998. The unusual type P[9], G3 and a few mixed infections were detected. Sixteen percent of the rotavirus-positive samples were nontypeable.

Randomised trial of effect of vitamin A supplementation on antibody response to measles vaccine in Guinea-Bissau, west Africa

WHO has recommended vitamin A supplementation for children aged 6 months or older in developing countries at the same time as immunisation. One study has reported significantly lower seroconversion ratios among children who have received vitamin A supplements with measles vaccine at age 6 months. The aim of our study was to assess the effect of vitamin A supplementation on antibody response to measles vaccination at age 9 months, which is the more common age for immunisation in developing countries. In an urban community in Guinea-Bissau, we did a randomised, double-blind, placebo-controlled study of the effect of simultaneous vaccination and vitamin A supplementation in 462 children who received either a two-dose schedule of measles vaccine at the ages of 6 months and 9 months (150 infants) or one dose of measles vaccine at age 9 months (312 infants). Children were followed up to the age of 18 months and a blood sample was then collected to assess the antibody response. 397 (86%) of the children took part in the follow-up (52 [11%] had moved and 13 [3%] had died). Among children who received a two-dose vaccine schedule, seroconversion was 98%. There was no difference in seroconversion or geometric mean titre (GMT) for children receiving vitamin A compared with children receiving no supplement. Among children receiving only one dose of measles vaccine at age 9 months, seroconversion was 95%. The GMT was significantly higher in children receiving vitamin A than in those receiving no supplement (3704 vs 2439 mIU; GMT ratio 1.52 [1.22-1.88]). The effect on plasma antibody concentration in the blood was stronger for boys (3902 vs 1916 mIU; GMT ratio 2.04 [1.53-2.72]) than for girls (3502 vs 3017 mIU; GMT ratio 1.16 [0.85-1.58]) who had received vitamin A with measles vaccine. In a multivariate analysis of variance adjusted for sex, vitamin A supplementation was associated with higher antibody titres (p < 0.001). There was a significant interaction between vitamin A supplementation and sex (p = 0.02). There is no indication that simultaneous administration of measles vaccine and vitamin A supplements has a negative effect on measles immunity. Among the children who had received two doses of measles vaccine at the ages of 6 months and 9 months, supplements of vitamin A had no significant effect. Among children only receiving one dose of measles vaccine at age 9 months, 100,000 IU vitamin A increased antibody concentrations, especially for boys.

Serial CD4 and CD8 T-lymphocyte counts and associated mortality in an HIV-2-infected population in Guinea-Bissau.

In an urban community in Guinea-Bissau, we followed a cohort of human immunodeficiency virus type 2 (HIV-2) seropositive individuals (N = 47) and seronegative controls (N = 82). T-lymphocyte subset determinations were done in 1988, 1990, and 1992. Serial determinations of CD4 percentages, CD8 percentages, and CD4/CD8 ratios for the same individual were stable for 31 seropositive and 51 seronegative individuals with repeated measurements. We found no significant differences in the changes during a 2- or 4-year period in CD4 percentages, CD8 percentages, absolute CD8 T-lymphocyte counts, CD4/CD8 ratio, white blood cell counts, lymphocyte percentages, and absolute lymphocyte counts for HIV-2-seropositive compared with HIV-2-seronegative individuals. Only absolute CD4 T-lymphocyte counts changed more for the HIV-2-seropositive than for HIV-2-seronegative individuals (p = 0.037). HIV-2-infected individuals who lived with an HIV-2-infected spouse had a lower CD4/CD8 ratio and had higher mortality than HIV-2 infected individuals who lived with an uninfected spouse. However, there were no significant differences in immunological and hematological values for the 8 HIV-2 seropositive individuals who died and the 39 who survived in the 8-year follow-up period. In conclusion, progression of immunosuppression in HIV-2 infection seems to be slower than in HIV-1 infection and may not be inevitable in all individuals.

Does age at the start of breast feeding influence infantile diarrhoea morbidity? A case-control study in periurban Guinea-Bissau.

Colostrum protects the newborn from intestinal infection by its content of secretory immunoglobulin A and other immediately acting factors. It may also induce maturation of the child's gastrointestinal immune defences, thus contributing to the protection against diarrhoeal disease later in infancy. To test this hypothesis, a case-control study on breast feeding and diarrhoea was carried out in a periurban community in Guinea-Bissau. The child's age at the start of breast feeding was ascertained soon after birth (n = 279). Subsequent cases of acute diarrhoea (n = 66) were identified at 3-monthly examinations, and four concurrent controls were randomly selected among attendants. Three separate estimates of association showed that the cases tended to have started breast feeding later after birth than the diarrhoea-free controls, but no single test was statistically significant. Early breast feeding might have consequences for diarrhoeal morbidity after the neonatal period.

The effects of HIV-2 infection in a rural area of Guinea-Bissau.

To investigate the clinical and immunologic effects, and pattern of mortality associated with HIV-2 infection. A rural community in Guinea-Bissau. Serologic screening of 2774 subjects aged > 14 years followed by studies of the prevalence of clinical and immunologic abnormalities among 133 subjects with HIV-2 infection and 160 seronegative controls, and surveillance of mortality among all subjects who were screened during a mean of 2 years of follow-up. Generalized lymphadenopathy was the only clinical abnormality significantly associated with HIV-2 infection. Infection was associated with lower CD4 counts and higher beta 2-microglobulin and neopterin levels. During follow-up, 5.5% of infected subjects died compared with 1.8% of the seronegatives (rate ratio adjusted for age and sex, 3.5; 95% confidence interval ((CI), 1.8-6.7). Proportional hazard regression analysis showed that the rate ratio varied with age (P = 0.003) and there was some evidence that the excess of mortality in infected subjects was, in absolute terms, least in the oldest subjects (trend test; P = 0.08). The findings support previous suggestions that HIV-2 is less pathogenic than HIV-1; the data also suggest that mortality associated with infection may be lower in older subjects.

Long–term survival in trial of medium–titre Edmonston–Zagreb measles vaccine in Guinea–Bissau: five–year follow–up

A trial of protective efficacy which compared medium-titre Edmonston-Zagreb (EZ) measles vaccine (10(4.6) p.f.u.) from the age of 4 months with the standard Schwarz (SW) measles vaccine given from the age of 9 months was started in an urban community in Guinea-Bissau in 1985. Because trials of high-titre measles vaccine have found increased mortality among female recipients, we examined whether EZ medium-titre vaccine was associated with any long-term impact on mortality, suppression of T-cells, or growth. The mortality rate ratio over 5 years of follow-up was 1.12 for EZ children compared with children in the standard group (P = 0.63). Seventy-five percent of the children still residing in the area at 5 years of age took part in an immunological and anthropometric examination. There was no difference in T-cell subsets between the two groups. There was no difference in mid-upper-arm circumference, but EZ children were significantly shorter than the children in the standard group. In conclusion, medium-titre EZ was not associated with reduced survival or persistent immunosuppression.

The epidemiology of HIV infection in a rural area of Guinea-Bissau.

To determine the prevalence of HIV infection and its relationship to age, sex and other factors. Cross-sectional survey of a rural community in Guinea-Bissau. Questionnaire-administration and screening of sera from subjects aged > or = 15 years. Of the 2770 subjects tested, 220 (7.9%) were HIV-2-seropositive, four (0.1%) were HIV-1-seropositive and 10 (0.4%) were dually reactive. Overall prevalence of HIV-2 was 9.3% in women, peaking at 17.2% in the 35-44 age group, and 6.6% in men, peaking at 19.1% in the 45-54 age group. The mean age of the four subjects with HIV-1 infection was 24 years, which was significantly lower than those with HIV-2 infection. HIV-2 infection was more prevalent among women who were widowed or divorced, women whose husbands were living away from the study area, and women who had lived in the capital, Bissau. The majority of subjects with an infected spouse remained uninfected and none of the women aged < 25 years whose husbands were infected were seropositive. The prevalence varied significantly between settlements within the study area. The pattern of HIV-2 infection in this rural community has similarities to that found in urban Bissau, and prevalence in both areas peaks in older subjects than in HIV-1 foci. The findings support previous suggestions that HIV-2 is not a recent introduction to Guinea-Bissau, and that it is less pathogenic and less readily transmitted than HIV-1.